body {  
    font-family: Arial, sans-serif;  
    margin: 0;  
    padding: 20px;  
}  
  
header {  
    display: flex;  
    flex-direction: column;  
    align-items: center;  
}  
  
.nav-bar {  
    display: flex;  
    flex-direction: column;  
    align-items: center;  
}  
  
.nav-item {  
    display: flex;  
    align-items: center;  
    justify-content: center;  
    width: 150px;  
    height: 50px;  
    background-color: #8BC34A; /* 绿色背景 */  
    color: white; /* 白色文字 */  
    border: none;  
    border-radius: 5px;  
    margin-bottom: 10px;  
    cursor: pointer; /* 鼠标悬停时变为小手 */  
}  
  
.rank {  
    font-size: 20px;  
    margin-right: 5px;  
}  
  
.